For many years it has been common practice to prepare cured bacon by treating green (uncured) bellies with a curing solution (hereinafter "pickle") and then smoking the cured bacon to impart a desirable flavor. A major component of the pickle is sodium nitrite which inhibits the germination of Clostridium botulinum spores, thus ensuring that the cured bacon will be free of the deadly toxin produced by this bacterium. In recent years, however, much controversy has surrounded the use of sodium nitrite because there have been allegations that residual nitrite from the pickle can react with organic amines present in various cured pork products to form carcinogenic nitrosamines. This problem is accentuated with bacon because nitrosamine formation is induced by the elevated temperatures encountered when the bacon is cooked for consumption; i.e., those exceeding 300.degree. F.
Many approaches have been considered in seeking a remedy to this problem and proposed remedies have included eliminating nitrite from the pickle or reducing residual nitrite levels in the cured product. Neither of these approaches is particularly satisfactory, however, because there is presently no suitable substitute for nitrite, and because reducing nitrite levels could increase the likelihood that C. botulinum spores would grow in the cured bacon.
Conventional pickle also contains a number of ingredients in addition to sodium nitrite. These include buffering agents such as sodium tripolyphosphate to stabilize the nitrite, agents to facilitate curing such as sodium erythorbate or ascorbic acid, and sodium chloride. In certain instances the buffer can be particularly useful because sodium nitrite is unstable in the presence of acid. For example, a pickle having a pH of 6.7 will show essentially no depletion of nitrite after 24 hours whereas pickle having a pH of 5.9 can show a 60% decrease in nitrite after 24 hours. The advantages and disadvantages of using buffers in pickles containing nitrite are well documented in the art.
Cured bacon has typically been prepared by immersing whole green bellies in pickle or by injecting the pickle directly into the green bellies. Commercial procedures most commonly involve injection of the bellies because the curing process can be rapidly and efficiently completed. When cured in this way, a quantity of pickle usually constituting 8-15% of the weight of the meat is injected; thus, for example, if a 7-kilogram bacon belly were pumped (i.e., injected) with pickle at the level of 10%, a quantity of 700 grams of pickle would be used.
Traditionally, cured bellies were smoked by exposing them to direct smoke in a smokehouse; however, the direct smoking of meat has a number of disadvantages and recent years have seen the development of a variety of liquid smoke compositions which are now in wide use. A number of U.S. patents disclose procedures for preparing and applying such products. For example, in U.S. Pat. No. 3,106,473, C. M. Hollenbeck describes a process for preparing an aqueous liquid smoke by counter current extraction of wood smoke; in U.S. Pat. No. 3,445,248, K. Miler et al. describe a method for preparing a refined liquid smoke extract suitable for use in sausage; in U.S. Pat. No. 3,480,446, C. M. Hollenbeck describes a method for preparing a smoke-flavored edible oil by extracting an aqueous smoke solution with oil; and in U.S. Pat. No. 3,523,802, R. H. Wandel et al. describe a process for preparing an aqueous liquid smoke particularly applicable to superficially treat hot dogs and smokey links, the liquid smoke being prepared by treating an aqueous smoke solution with a non-toxic oxidizing agent in order to destroy certain color-forming constituents of the smoke.
The basic compositions of several liquid smokes have been extensively investigated and it is reported that they contain three basic classes of components: acids, phenols and carbonyl compounds, all of which contribute to the flavor and color characteristics of smoked products. The phenols, which are acidic in nature, and the acids account for the low pH of liquid smoke, which is generally on the order of 2 to 3. Furthermore, the phenols contribute greatly to the smokey flavor imparted by the liquid smokes. The carbonyl compounds, which are more neutral, constitute a major portion of the color-forming components. These components give the meat surface a desirable brownish smoke color when the liquid smoke is applied by spraying or atomization.
Liquid smokes have found wide commercial acceptance. Those used most often are generally either aqueous or non-aqueous (oil based) solutions, although powdered forms of liquid smokes are also available. Examples of such smokes are CharSol which is an aqueous solution of hardwood smoke that has been processed to remove particulate matter; CharOil which is a vegetable oil extract of CharSol; and CharDex, which is a malto-dextrin that has been treated with CharSol and spray dried. These products are produced by Red Arrow Products Company. CharSol and CharOil are primarily used for surface applications to pork products and for direct addition to sausage products, whereas CharDex is primarily useful for addition to meat products that cannot tolerate added moisture, such as certain sausage products.
The technical literature distributed by Red Arrow indicates that CharSol and CharDex may be added to curing solutions which do not contain nitrite and that the resulting solutions can be pumped without difficulty. However such liquid smokes have not been successfully added to curing solutions containing nitrite and pumped on a commercial basis. There are a number of reasons for this, many of which are associated with the physical character of such compositions.
Liquid smoke is acidic in nature and the nitrite in the pickle is acid sensitive. Accordingly, if liquid smoke is added to the pickle, it is necessary to buffer the pickle with compounds such as sodium tripolyphosphate in order to avoid the liberation of nitric oxides. Although buffering can overcome that problem, it raises the pH so that certain components of the liquid smoke, particularly, the phenolic compounds, tend to separate from the aqueous phase. Such precipitated matter tends to cause plugging of the injection needles and the non-homogeneous nature of the mixture makes it is virtually impossible to uniformly inject the bellies.
In addition, there is also another reason for excluding liquid smokes from the pickle. Liquid smokes contain significant levels of phenols and there have been recent suggestions in the scientific literature that phenols will enhance the rate at which organic amines are nitrosated. For example, R. Davies and D. J. McWeeny in Nature 226, 657 (1977) stated "It therefore seems that at suitable concentrations the presence of phenols can lead to an enhancement of the rate of nitrosamine formation". Thus, the addition of liquid smoke to the curing pickle might be expected to increase N-nitrosamine levels. This factor, in combination with the other disadvantages noted above made it clear at the time the present invention was made that the problems associated with incorporating liquid smoke into pickle containing nitrite outweighed any advantage that might be derived.
We have discovered a method whereby the foregoing problems are overcome and green bellies can be pumped with a specially modified pickle containing liquid smoke. Moreover, we have discovered, to our surprise, that the resulting bacon contains reduced levels of N-nitrosamines, while at the same time the levels of residual nitrite present in the uncooked cured product remain relatively unaffected, thus ensuring that the germination of C. botulinum spores will be prevented. In addition, the flavor of the product when cooked for consumption is remarkably improved.
Accordingly, one object of the present invention is to provide a process to prepare a cured bacon product which will be safe from contamination by deadly C. botulinum toxins.
A second object of the present invention is to provide a process for preparing cured bacon which, when cooked for consumption, will contain relatively low levels of the N-nitrosamines which are alleged to be carcinogens.
Still another object of the present invention is to prepare cured, smoked bacon which, while meeting the aforementioned objectives, will have enhanced flavor characteristics and thus will be more acceptable to consumers when cooked for consumption.
These and other objects of the invention will become apparent from the detailed descriptions of preferred embodiments which follow.